So, I have a few details to add and work out... but the first draft is looking good.. I'm going to add a few things (mounting holes for the filter adapters and such), and clean up the code..right now I don't think it'd print too well...  I also need to separate all the parts such as the wheel itself, and the body, etc.. into individual files...

Here's a couple shots that show what is going on pretty well..  

This one shows the inside... the big gear is the filter wheel and the holes are where the filters mount..the whole thing spins around and allows you to select the filter for the exposure your working on..The two gears below are the stepper motor drive pinion(right) and the optical encoder pinion (left), which allows the system to track the filter position..

The backside...Showing the stepper motor, the exit beam path, the screw holes and the mounting hole for the optical encoder...

I expect I'll have this done in the next couple of days..  I'll print it up and post it here as soon as I do!  

And then I'll be on to laying out the collimating lens / entrance slit and then it's on to the actual spectrometer! That should be fun..  I need to purchase a new diffraction grating and a couple of mirrors soon...